This proposal concerns the development of a new fluid dispensing technology for biomedical research. The heart of the system is the piezoelectric ink-jet, a solid-state device that can "jet" droplets of fluid onto remote targets with exquisite spatial, temporal, and volumetric precision. Both the aiming of the jets and the dispensing of drops can be remotely controlled, allowing drops to be dispensed across the surface of any biological sample according to preselected spatial and temporal programs. In our prior research (Phase I, SBIR) on biomedical applications of ink- jet technology, we demonstrated that the jets could be used to dispense microdroplets of drugs or histologic reagents onto both living brain slices and histologic sections. By the use of this"microjet" dispensing system, it was possible to perform neurophysiologic/pharmacologic as well as histoloanalytic experiments with previously-unattainable resolution. In the present work, we propose to construct and evaluate three prototype microjet systems for use in specific biomedical applications. The instruments will be used for (i) dispensing microdrops and drugs into live brain slices, (ii) dispensing microdrops of reagents for histochemistry onto tissue biopsy samples, and (iii) dispensing microdrops of photoabsorptive dye onto tissues that are to be heated during laser microsurgery.